Outlook now lets subscribers switch off your preview text

Microsoft rolled out a change to Outlook this month that hands subscribers a switch you don't control. As of a July 2026 update to Outlook on Windows and Outlook on the web, users can now set their inbox preview to two lines, one line, or none at all. Roadmap ID 564610, general availability across commercial and government cloud environments through the month.

For a channel that has spent fifteen years leaning on preview text as free extra copy, that's a real shift.

What actually changed

Outlook's inbox has always shown a snippet of the email body next to the subject line, the preview text or preheader. Marketers have used that space deliberately for years: a second line of persuasion, a discount code, urgency copy, whatever didn't fit in the subject line itself.

Until now, how much of that snippet a subscriber saw was mostly out of their hands, dictated by client version and screen width. Microsoft has turned it into an explicit setting. Subscribers can now choose to see two lines, one line, or nothing beyond the subject line itself.

Rollout is staggered. Some Outlook on the web tenants already have it. New Outlook for Windows is catching up on its own schedule. There's no admin policy or PowerShell control documented yet, so this reads as a straight user preference, not something IT departments will manage centrally.

Why this matters more than it looks

Preview text has been doing real work in email campaigns. Retailers use it to stack a second hook after the subject line: free shipping thresholds, stock warnings, countdown copy. Some flows are built assuming that second line renders every time.

That assumption breaks the moment a subscriber sets their inbox to zero lines. Your subject line has to carry the entire pitch alone, because there's no guarantee of a safety net underneath it.

Outlook holds meaningful inbox share among Australian consumers and a larger share again in B2B and corporate email, so this isn't a rounding error. Any brand that leans on preview text for the second half of a subject line pairing needs to know some real slice of their list won't see it.

What brands need to do

Audit your last handful of campaigns and read the subject line on its own, no preview text attached. If the subject line alone doesn't make sense or doesn't carry the offer, that campaign was relying on a line of copy that a growing number of subscribers will never see.

Front-load anything that actually drives the open: the offer, the deadline, the specific product, not a teaser that only pays off once preview text fills in the gap. Preview text should still get written well, plenty of subscribers will still see it, but stop designing subject lines that depend on it.

If you're running Klaviyo, Mailchimp, or another ESP with a live preview pane, check how your templates look with the preview text field left blank entirely. That's the worst case you now need to design for, not an edge case.

Not sure how your subject lines would hold up if preview text disappeared for a chunk of your list? Run the free audit, ten questions on your automations, deliverability, and reporting, with a score and a prioritised list of what to fix first.